Cation Substitutes in Lithium Batteries -Lithium - Ion Battery Equipment

Cation Substitutes in Lithium Batteries -Lithium - Ion Battery Equipment

From smart phones to electric vehicles, lithium-ion batteries (LIBs) provide power for everything. With the progress of technology, lithium-ion batteries have made significant progress and completely changed our world. The next step of technological progress is to develop better batteries to provide more lasting power for electronic devices. A promising technique to improve battery performance involves atomic substitution of positive ions or cations in cathode materials. However, it is complex and expensive to systematically test different cations to determine the ideal cation, which makes us have to consider simulation as the only feasible option to narrow the selection range.(Lithium - Ion Battery Equipment)

Some research reports that battery life and thermal stability have been improved based on their findings using simulation based methods. However, this improvement in turn reduces the discharge capacity of the battery, that is, the energy that the battery can provide in a single discharge. Therefore, it is necessary to find cation substituents that can improve discharge capacity.

In this context, a team of scientists led by Professor Ryo Maezono of the Japan Advanced Institute of Science and Technology (JAIST) extensively screened different cations in order to partially replace nickel in nickel based LIB, thereby improving the discharge capacity of the battery.

The discharge capacity can be determined by the discharge curve, that is, the voltage change during charging and discharging, explained Professor Maezono. We use first principle calculations to evaluate the discharge curves of materials, which in turn determine their discharge capabilities. However, the calculation cost of these calculations is very high, so we integrated other methods to narrow down the candidate for cation substitution. To our knowledge, this is the first study to successfully predict cation substitution to increase battery capacity. This breakthrough research has been published in the latest issue of Physical Chemistry Journal C.

A prominent strategy for successfully predicting the discharge voltage curve is the strong constraint and appropriate specification (SCAN) function. However, this method is impractical for a wide range of screening due to the large amount of computing costs involved. Therefore, the research team began to use relatively cheap technologies, such as density functional theory and cluster expansion, to determine appropriate cation substitution candidates, and then applied SCAN function to inferred candidates to ensure the reliability and accuracy of voltage prediction.

The screening process showed that the maximum discharge capacity could be obtained by partially replacing nickel with platinum and palladium in nickel based lithium. These results are consistent with the experimental data, and verify the proposed method.

Although Professor Maezono stressed the need for more research, he was optimistic about the future of their low-cost screening process. "Our findings indicate that substituents such as rhenium and osmium provide high discharge capacitances. However, these elements are rare and expensive, and it will be challenging to put them into practical use. We need further research to reduce substitutions, multiple element substitutions or anion substitutions to achieve the same effect." "That said, our new computing technology will accelerate the search for optimal materials, improve battery performance at a lower cost, and enable us to replace most of the existing power sources with carbon free alternatives.



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